Problem: Luis starts counting at 34, and he counts by fours. If 34 is the 1st number that Luis counts. what is the 9th number that he counts?
Solution: What is the first number that he counts? $34$ What is the second number that he counts? $\begin{align*}&34 + 4 \\ &= 38\end{align*}$ What is the third number that he counts? $\begin{align*}&34 + 4 + 4 \\ &= 34 + (2 \times 4) \\ &= 42\end{align*}$ What is the 9th number that he counts? $\begin{align*}&34 + (8\times4) \\ &= 34 + 32 \\ &= 66\end{align*}$